This invention relates to a temperature responsive fluid control valve. Temperature responsive valves are presently used to control fluid flow between a pressure or vacuum source and a fluid actuator, as for control of a vehicle radiator shutter or the like. Such a valve typically has a thermoresponsive element positioned in the engine coolant through a port in the engine. See e.g. U.S. Pat. Nos. 3,853,269 and 3,135,495. The shutter is therefore operated in response to engine temperature for control of the engine temperature. See e.g. U.S. Pat. No. 3,198,298. Some engines also employ a fan drive clutch which is operated in response to engine temperature conditions. Such a clutch is typically controlled by a second control valve with its higher temperature thermoresponsive element also in the engine coolant via a second port in the engine. The shutter regulates the amount of air allowed to flow through the radiator. The fan clutch regulates the amount of air dynamically drawn or blown, i.e. propelled through the radiator.
Optimally, these two separately functioning systems should operate cooperatively to create a large range of variable air flow conditions for engine temperature control. But, because the two operate independently, their operation can be mutually conflicting. This possibility of mutual interference can be caused for example by one or both of the units not being accurately preset or not properly located in the engine cooling system or one or both not functioning accurately for some other reason. At best they require the expense of two control valves and two ports in the engine block to the coolant systems.